How Add column with modification date

[exll]

Hello,
Maybe anyone know how i can add new column with date modify tickets to user Interface.
I know that I have to do it in a file CustomerTicketOverView.dtl, but I do not know what parameter to add lines.
For example I added lines <td class="GG"> $ QData {"Created", "20"} </ td> who display ticket creation date.

best regards